最小Higgs模型中带电标量粒子与顶夸克在LHC上的产生

除了类标准模型中的希格斯粒子,最小Higgs模型（LH）还预言了带电的标量粒子Ф±的存在.研究了该带电的标量粒子与单个顶夸克在大型强子对撞机（LHC）上的联合产生过程.计算结果表明,在大部分参数空间内产生截面在0.1 fb量级,很难通过该过程探测带电标量粒子的信号,但为区分其他新物理模型中的带电标量粒子,如最小超对称（MSSM）模型中的带电Higgs玻色子提供一个途径.将来的LHC实验可以通过该过程进一步检验或排除LH模型.     

大强子对撞机(LHC)物理

欧洲核研究中心(CERN)建造的大强子对撞机(LHC)是世界上能量最高的粒子加速器。它的设计是,使两个运动方向相反的粒子束流对撞,每个束流包含能量各为3.5 TeV的质子(1 TeV即10~(12)电子伏特)或能量各为574 TeV的铅核(其中每个核     

线性对撞机上R宇称破缺超对称效应研究

在R宇称破缺的最小超对称模型下,研究了线性对撞机上轻子数破缺的耦合对top夸克对新的产生机制,并由此对tt产生截面的新贡献.研究结果表明,在允许的参数范围内,R宇称破缺的相互作用不仅可以显著地改变top夸克对的产生截面,而且对top夸克的极化以及前后不对称性都有显著影响.     

LHC上三规范粒子的伴随产生

大型强子对撞机上三规范粒子的伴随产生可以用来检验标准模型中的四线耦合的特性。拟在标准型的理论框架下研究大型强子对撞机(LHC)上W+W-Z的产生过程,计算了该过程的量子色动力学(QCD)的次领头阶(NLO)的修正,给出了这两个过程在不同对撞能量下的截面,分析了这两个过程末态粒子的横动量分布。研究了该过程的半轻子衰变,以及在CMS探测器上的信号。     

正负电子对撞机上三规范粒子的伴随产生

在标准型的理论框架下研究了国际直线对撞机(ILC)上W⁺w+w^-Z、ZZZ的产生过程,给出了这两个过程在不同对撞能量下的截面,结果显示这两个过程的反应截面都很大,有足够的事件进行实验分析.还给出了这两个过程在能量为500GeV时末态W和Z粒子的横动量分布.     

味改变标量耦合与强子对撞机上的tγ(Z)产生

在顶色辅助人工色(TC2)模型框架下,通过计算味改变标量耦合在树图级下对tγ、tZ产生的贡献,发现:在TC2模型参数空间内,在Tevatron对撞机实验上tγ(Z)的产生截面非常小.然而,在LHC对撞机实验上,可以通过末态γlvb(l+l-lvb)较容易地探测到味改变标量耦合对tγ(Z)产生的虚效应.     

一个轻的赝标玻色子与轻子的味改变过程

在双Higgs二重态模型Ⅲ下计算了一个轻的赝标玻色子对轻子味改变过程li→ljγγ和li→lje e-的贡献.发现的衰变宽度一般情况下在10-14GeV的量级,并且运用li→lje e-的实验结果对li→ljγγ过程的分支比进行了估计,其中对μ→eγγ分支比的估计比实验改进了大约两个量级.     

LHC上顶夸克极化效应的研究

在顶色辅助的人工色模型框架下,在LHC上研究了应对的产生过程中顶夸克的极化效应,在计算过程中,运用了CTEQ5部分子分布函数和螺旋度投影算符的方法,结果表明：考虑极化后,在绝大部分参数空间内,截面修正大于15％,该修正在实验上完全可以探测,因此,在LHC上,人们有希望通过应的产生过程发现TC2模型存在的迹象。     

强子对撞机上通过顶夸克自旋不对称性分布研究TC2模型

在顶色辅助的人工色理论下,在强子对撞机上通过顶夸克-反顶夸克对的产生过程中自旋不对称性的分布研究顶夸克的极化效应,在计算过程中,运用了CTEQ6部分子分布函数和螺旋度投影算符的方法.研究结果表明：在Tevatron上顶夸克的极化效应太小不可探测;参数选取得当,该效应可达20%,在LHC上可以探测到.因此,顶夸克的极化效应提供了一种切实可行的检验顶色辅助的人工色模型的方法.     

荷电PG玻色子对B介子稀有衰变B→Xs，dvv,Bs,d→l^＋ l^－的贡献

在顶夸克辅助的人工色(topcolor-assisted technicolor(简称TC2))模型下，计算荷电玻色子(pseudo-Goldstone bosons(简称PGBs))对稀有衰变B→Xs,dvv,和Bs,d→l^ l^-的贡献，并把它们与标准模型的结果相比较，发现在所考虑的参数空间，PGBs对所研究的分支比提高10到30倍，其中top-pion对B介子稀有衰变的贡献起主导作用，理论预言仍与目前的实验数据相符合。这些修正将导致有可能发现新物理存在的证据或对TC2模型本身的严格限制。     

Discovery of SM Higgs boson in ATLAS experiment

The Large Hadron Collider (LHC) at CERN — the most expensive and complex instrument mankind has ever built to address some of the most fundamental questions of Nature — is colliding proton-on-proton at high energy since November 2009. The full data set delivered by the LHC over the last 4 years has been analyzed by the ATLAS and CMS experiments in their pursuit of the Higgs boson, the particle responsible for generating masses for the basic building blocks of matter. In this article I discuss in detail the building and commissioning of the detector, search strategy and results obtained by the two experiments with special emphasis on ATLAS.     

Discovery of a boson at CERN and Indian connections

In this article, we provide a bird’s-eye view of the discovery of a new particle at CERN in Geneva, which very much seems like the long sought-after Higgs boson. We conclude on a celebratory note of the Indian connection to this epochmaking discovery.     

Search for future viands

Algae and fungi have good prospects to be exploited as alternative sources of food. Both these groups of organisms are rich in food value, especially in their protein component. Their large-scale utilization may help to minimize food crises as well as malnutrition around the world.     

The Search for Virtue

ABSTRACT

Sixty accredited MSW programs were surveyed to determine whether there were significant differences between those programs offering discrete ethics courses and those not doing so on a number of ethics education related variables. Results suggest virtually no significant differences on the variables examined, with the exception that programs offering discrete courses more often expose students to literature on the broad topic of moral philosophy. Also examined was the extent to which all of the programs surveyed were following the pedagogical recommendations of the ethics education literature reviewed. The results suggest that many MSW programs are not following these recommendations in a number of respects. The implications of these findings are discussed, and specific suggestions are offered for those faculty concerned with the ethics component of their course offerings.     

A Search for Meaning

This article describes an active learning demonstration to increase student interest in and involvement with the topic of research ethics and deception. Students received false, low feedback on an exam and then completed a faculty evaluation form. The class was then informed about the deception and the research issue (the impact of grades on evaluations). Students then discussed their immediate reactions to the experience of deception. Two weeks later students wrote a reflective essay that described how their reactions and views had evolved. The discussion and essays indicated that the demonstration produced a high level of student involvement, empathy toward research participants, and self-examination.